Combine Bench Over Time

Initial Research Question

Each of the thirty-two National Football League (NFL) Franchises (teams) rosters a total of 53 players, with up to 16 on a “practice squad”, and the remaining on the official team roster
After every season, each team has the opportunity to draft players from a candidate pool
Each player wanting to be drafted participates in the NFL Scouting Combine
I would like to know which biometrics of Combine participants are the best predictors of the number of bench press repetitions one can perform?

NFL Scouting Combine

Figure 1: Player Sprinting the Forty Yard Dash at the NFL Scouting Combine, image from (“Washington’s John Ross sets 40-yard dash record at NFL Scouting Combine” https://www.wkyc.com/article/sports/nfl/nfl-draft/washingtons-john-ross-sets-40-yard-dash-record-at-nfl-scouting-combine/95-419799888)

225-lb Bench Press

Figure 2: Official Bench Press bench used in the NFL Scouting Combine, image from (“NFL Combine: Which player did the most bench-press reps on Friday?” https://www.al.com/sports/2019/03/nfl-combine-which-player-did-the-most-bench-press-reps-on-friday.html)

Combine Data

Table 1: Select columns of the first five rows of the cleaned and condensed `combine` data set.
name	position	heightinchestotal	weight
Ameer Abdullah	RB	69	205
Nelson Agholor	WR	72	198
Jay Ajayi	RB	72	221

Player Bench Press Repetition Data

Figure 3: Exploratory plot showing the average number of bench press repetitions from 1999 to 2015.

Player Weight Data

Figure 4: Histogram of combine participant weight values.

Player Height Data

Figure 5: Histogram of combine participant heights.

Player Arm Length Data

Figure 6: Histogram of combine participant arm lengths.

Player Weight and Number of Repetitions

Figure 7: Plot showing relationship between number of bench press repetitions and weight, one plot for each year included in the data set. Weight is in units of pounds (lbs).

Player Height and Number of Repetitions

Figure 8: Plot showing relationship between number of bench press repetitions and height, one plot for each year included in the data set. Height is in units of inches (in).

Player Arm Length and Number of Repetitions

Figure 9: Plot showing relationship between number of bench press repetitions and height, one plot for each year included in the data set. Arm Length is in units of inches (in).

Model Estimates for Number of Repetitions

Figure 10: Linear regression predicting the number of repetitions of bench press a player can perform based on their height, weight, and arm length.

Bench Press Repetition Predictions

Figure 11: The results of a linear regression predicting the number of repetitions of bench press a player can perform based on the player’s height, weight, and arm length.

Model Estimates for Player Position

Figure 12: A K-Nearest-Neighbors classification categorizing players by which group of positions they play on the field, as an offensive/defensive lineman or secondary player.

Player Position Model Accuracy

Table 2: Accuracy of the K-Nearest-Neighbors model, displayed in the `.estimate` column.
.metric	.estimator	.estimate
accuracy	multiclass	0.6410516

Player Position Model Performance

Figure 13: Truth table of the K-Nearest-Neighbors classification where the values on the diagonals are successful identifications, and any others are unsuccessful identifications.

Conclusions

Evidence supporting the hypothesis that player weight, height, and arm length has an impact on NFL Scouting Combine bench press performance
Individual player position is not likely to have an impact on their bench press performance
Lack of evidence that player position can be determined solely by observing Combine statistics